The first discussion group at the AF Conference featured a debate on the eternal problem of how all the birthdays fit in (as we know, they don't).
We were discussing the fact that, given the author's note at the beginning of Marlows and the Traitor, which says that Peter must be 14 when it starts (Easter holidays), and the fact that Ginty becomes 15 on January 6th in Peter's Room, there is no way Peter and Ginty could be siblings. Various theories were suggested to explain this 3-4 month gap, such as them being twins with a very large delay between births, and Ginty being the adopted love-child of Geoff Marlow and Auntie Mollie, which accounts for him having given his wife a necklace when she was born, and the trip to Paris.
These thrilling speculations were slightly crushed by Sue Sims telling us that she had brought up the birthdays issue with Forest and Forest had said oh yes, she was never very good at dates (I'm paraphrasing here. If any of you who were there remember exactly what she said, or happen to be Sue Sims, please correct me).
Huh! I have devoted a great deal of time to working out Marlow age differences and trying to make them make sense. On my pre-conference read-through I even went so far as to write down every piece of evidence as I went along. After all this effort, it's a bit galling to find out that Forest just wasn't all that bothered.